Transitional geology and its effects on development and longwall mining in Pittsburgh Seam

This paper presents the geologic and ground control challenges that were encountered by Consol Energy＇s coal mining operations in southwestem Pennsylvania, USA. Geologic encounters, such as sandstone- to-limestone geology transition, massive sandstone channels, shale channels, pyritic rich green claystone, laminated roof, and soft floor, have significantly impacted the development and longwall mining in Consol＇s Pittsburgh Seam coal mines. Experience from different mines shows that, in the sandstone-to-limestone geology transition zone, 1.83 m high-tension, fully-grouted primary bolts employed along with 4.88 m cen- ter cable bolts at every other strap greatly improved beam building and ensured proper anchorage into the competent roof. Hydraulic fracturing of the massive sandstone was often necessary to enhance caving of the massive sandstone behind the shields to relieve pressure at the face. The presence of soft floor coupled with presence of thick floor coal and deep cover, induced excessive headgate convergence during retreat of the first right hand longwall panel. In all, it is important to explore the roof and in-seam geology in detail to delineate normal and anomalous geologic conditions prior to and during development. With diligent geologic reconnaissance, geotechnical monitoring, and assessment, site-specific geotechnical solutions have been provided to mine operations to improve safety and productivity.

Geochemical anomaly and the causes of transition metal accumulations in late Permian coal from the eastern Yunnan-western Guizhou region

The concentration of 39 trace elements in coal from the late Permian taken from the eastern Yunnan-western Guizhou region was determined using inductively coupled plasma mass spectrometry. It was found that the mean content of Ti, V, Cr, Mo, Co, Ni, Y, and Zr is higher than the national average. The occurrence of Mn, Ni, and Co in the different coalfields is distinctly different. Most of the enriched transition metal elements exist mainly as inorganic minerals. In the Zhina coalfield, Co, Ni, and Nb are primarily associated with sulfur. Mn, Cs, and Mo are mostly sulfides. Almost all Co was organic and a significant part of the Ni is also organic in the Liupanshui coalfield. Cs, Co, and Ni are related to sulfur in the coal taken from eastern Yunnan. Carbonate is the main form of Mn in the coal from eastern Yunnan and the Liupanshui coalfield. Ti is the oxide in the coal samples where Ti is enriched. Zr is in the form of zircon in the samples where Zr is enriched. The situation for most of the transition metal elements is consistent with terrestrial genesis. Coal seams are universally influenced by the sea. The strongly seawater effected peat bog with a reductive and alkaline environment favors the relative enrichment of Mn. A reducing environment is conducive to transition metal element enrichment.

Evaluating provincial-level employment challenge during the coal transition in China

As China works to move away from coal in its energy system as a critical strategy to achieve carbon neutrality before 2060,there are several challenges which will affect the coal transition.One challenge that has not been fully explored is the impact on coal employment.There are millions of people employed in various sectors along the coal supply chain,including mining,processing,transport,and power generation.In this study,we developed a framework to understand the magnitude and characteristics of the employment challenges associated with the coal transition across provinces.Specifically,the magnitude and characteristics of the challenges are evaluated from multiple dimensions,including existing coal sector employment,coal production,coal consumption,GDP contribution from the coal industry,and coal mining productivity,to explore how the transition of the coal industry will likely affect different provinces.The results showed that provinces with large total coal employment today are often those with high coal production and consumption,high GDP contribution from the coal industry,and low productivity of coal mining.We found that employment impacts of a coal transition will not be equally distributed in China,as both the magnitude and characteristics of the employment challenges vary substantially across all provinces.It is therefore important to develop a tailored strategy to tackle specific needs for each province.

A U.S.‒China coal power transition and the global 1.5℃ pathway

As the world seeks to increase ambition rapidly to limit global warming to 1.5℃,joint leadership from the world's largest greenhouse gas(GHG)emitters-the United States(U.S.)and China-will be critical to deliver significant emissions reductions from their own countries as well as to catalyze increased international action.After a period of uncertainty in international climate policy,these countries now both have current leadership that supports ambitious climate action.In this context,a feasible,high-impact,and potentially globally catalytic agreement by the U.S.and China to transition away from coal to clean energy would be a major contribution toward this global effort.We undertake a plant-by-plant assessment in the power sector to identify practical coal retirement pathways for each country that are in line with national priorities and the global 1.5℃ target.Our plant-by-plant analysis shows that the 1.5℃-compatible pathways may result in an average retirement age of 47 years for the U.S.coal plants and 22 years for Chinese coal plants,raising important questions of how to compare broader economic,employment,and social impacts.We also demonstrate that such pathways would also lead to significant emissions reductions,lowering overall global energy-related CO_(2) emissions by about 9%in 2030 relative to 2020.A catalytic effect from the possibility of other countries taking compatible actions is estimated to reduce global emissions by 5.1 Gt CO_(2) in 2030 and by 10.1 Gt CO_(2) in 2045.